The Ashley Madison hackers alerted the company to the hack by making its computers play 'Thunderstruck' by AC/DC

AC/DC guitarist Angus Young. Getty Images North America Toronto Police just held a press conference to provide more information to the media about the hack of extra-marital affairs website Ashley Madison.

Police explained during the conference that the hackers revealed their presence to Avid Life Media, the company behind Ashley Madison, by playing the AC/DC song "Thunderstruck" using compromised company laptops.

Employees of Avid Life Media arrived for work as usual on July 12, but police said that when they opened their laptops, this messaged appeared:

BI

The ransom note said that if Ashley Madison wasn't shut down, hackers would release customer data on the internet. But that wasn't the only message the hackers had, they also played "Thunderstruck" to really get their message across.

Hackers often use compromised computers to send messages to companies. The same thing happened with the Sony Pictures hack, which saw the "Guardian of Peace" hacking team display this message on screens of computers connected to the Sony Pictures network: